The present invention relates generally to vehicle safety systems and more particularly to air bags and modules for protecting an occupant during a side impact collision.
Various side impact protection systems have been proposed as illustrated in U.S. Pat. Nos. 5,251,931, 5,324,072, and 4,946,191. In some of these systems the air bag is stored within the vehicle side door while in others the air bag is stored within the seat or head rest. Some air bags are designed to protect only the upper torso or the head of an occupant while others are sufficiently large to protect both. By studying the dynamics of a side impact crash it can be seen that the dynamic loading to the neck and head typically occurs later in time than the dynamic load to the side or lower torso of the occupant. As such it is desirable to provide an air bag in which inflation occurs rapidly to protect the side of the occupant and inflation gas is stored or communicated in the bag or bag section to protect the occupant's head.
It is an object of the present invention to provide an air bag for protecting an occupant during a side impact crash or collision. A further object of the invention is to provide for side impact protection using a bag in which a top portion or region of the air bag is filled to a higher pressure than a lower portion of the bag that typically comes into contact with the thorax of the body.
Accordingly, the invention comprises: an air bag comprising: a first side panel joined to a second panel and having a neck portion for receiving inflation gas from a cooperating gas inflator and first means for achieving a higher pressure in an upper chamber of the bag than in a lower chamber of the bag. This means may include coating the upper portion of each bag to insure that air flow through this portion is restricted or channeling a greater amount of inflation gas into the upper or head portion or the air bag to protect the occupant's head or by using a series of vents and valves separating a lower portion of the bag from the upper portion of the bag and selectively permitting inflation gas to enter into the upper portion of the bag. In addition, the first means may be obtained by using a tether that separates the air bag into an upper and lower chamber and which also acts to divert inflation gas into each chamber. The first means may also include a narrow seam or one elliptically shaped to channel inflation gas to one or the other chamber. Either seam may also be segmented to provide for flow passages between the chambers. In one embodiment inflation gas flows directly into both chambers while in another embodiment inflation gas is directed only into the lower chamber.